Physicists Confirm that Schrodinger's Cat Is Both Dead and Alive - Even in Two Different Boxes

What happens when you cut Schrodinger's cat in half? Apparently, you get two halves of a cat that are both alive and dead, as researchers from Yale University have just proven in a new experiment.

Don't worry, no cats were actually sawed in half for this experiment. Schrodinger's Cat refers to a thought experiment that illustrates the superposition of quantum particles, or their ability to be in multiple states at once. Just as quantum particles can exist as combinations of different states until they are observed, at which point they collapse into one state, a cat in an opaque box can be both alive and dead at once until it is observed (at least in the case of a cat that follows quantum rules).

For this experiment, rather than use an actual cat, researchers used microwave photons and forced them into a so-called "cat" state. Usually, these waves will oscillate in strength, but they can be coaxed into performing seemingly contradictory actions simultaneously.

"A mechanical analog of this would be a pendulum that is simultaneously oscillating to the left and to the right," study leader Chen Wang told New Scientist.

While other experiments have already demonstrated the superposition of quantum particles, this study took it a step further, and asked what would happen if the cat were in two boxes. They built two aluminum cavities with protons inside them, connected by a sapphire chip and an aluminum circuit, through which the protons could travel through. When this chip was turned on, the protons would oscillate at multiple frequencies, but the question was whether the two boxes would work together once the chip had been turned off. But they couldn't determine this by directly observing the boxes, since that would collapse the photons into one state or another.

"You can always ask the question, are you dead or alive?" Wang said. "But this question doesn't tell you whether it is a true quantum superposition, or whether you prepared half the chance of a dead one and half the chance of a live one."

So in order to answer this question, the researchers indirectly observed whether there was a "cat" state inside the two boxes by measuring the number of photons in each box. If there were a cat state that resulted from electromagnetic waves, there should be an even number of protons. When they measured the boxes separately, there were an odd number of protons, but when measured together, they turned up an even number of protons.

"That shows you that when you combine the two boxes, you get a true Schrödinger's cat state," Wang said.